Low power and Lossy Networks (LLNs), e.g., sensor networks, have a myriad of applications, such as Smart Grid and Smart Cities. Various challenges are presented with LLNs, as they often include lossy links, low bandwidth, low memory, and/or limitations on battery operation and processing capability, etc.
One particular issue that sometimes confronts LLNs is that they operate over very low bandwidth, making more dramatic the likelihood and impact of packet collisions, which increase with an increase in the number or length of messages. When LLNs are configured to send multicast messages, a relatively large number of acknowledgement messages (ACKs) may occur, overloading the LLN. This issue is particularly evident in large LLNs, e.g., where millions of nodes form the network.